@atlaskit/top-layer

Low-level top-layer primitives using the native Popover API (popover="auto") and <dialog> element.

Popup

Compound component for rendering content in the browser's top layer with CSS Anchor Positioning. Placement is owned by this compound: root provides it via context, Content applies it (CSS Anchor Positioning or JS fallback).

<Popup placement="block-end" onClose={handleClose}>
	<Popup.Trigger>
		<button>Open</button>
	</Popup.Trigger>
	<Popup.Content role="dialog" label="My popup">
		Content here
	</Popup.Content>
</Popup>

For default overlay styling (background, shadow, border-radius), see PopupSurface in the package examples (not currently a public API; we may expose it in a future release).

Popover

Low-level primitive: a <div> with the popover attribute and show/hide lifecycle only. No placement, no trigger wiring — use it when you need top-layer rendering with fixed or custom positioning (e.g. Flag uses Popover mode="manual"). For anchor-positioned content next to a trigger, use Popup instead.

Dialog

Compound component for modal dialogs using the native <dialog> element with .showModal().

{
	isOpen && (
		<Dialog onClose={handleClose} width="medium">
			<Dialog.Content>
				<Dialog.Surface>
					<Dialog.Header>
						<Dialog.Title>Heading</Dialog.Title>
						<Dialog.CloseButton />
					</Dialog.Header>
					<Dialog.Body>Content</Dialog.Body>
					<Dialog.Footer>Actions</Dialog.Footer>
				</Dialog.Surface>
			</Dialog.Content>
		</Dialog>
	);
}

Animations

Both Popup (and the low-level Popover) and Dialog support CSS-based entry/exit animations via the animate prop. Animations use @starting-style for entry and allow-discrete on display/overlay for exit — no JavaScript animation coordination required.

Presets are available from @atlaskit/top-layer/animations:

import {
	// Popover presets
	slideAndFade,
	fade,
	scaleAndFade,
	// Dialog presets
	dialogSlideUpAndFade,
	dialogFade,
} from '@atlaskit/top-layer/animations';

Popup animation

Pass a preset to Popup.Content (or to Popover when using the low-level primitive without placement):

import { slideAndFade } from '@atlaskit/top-layer/animations';

const animation = slideAndFade();

<Popup.Content animate={animation} role="dialog" label="My popup">
	Content
</Popup.Content>;

For overlay styling (background, shadow, border-radius), see the PopupSurface usage in the package examples.

Available popover presets:

• slideAndFade({ distance? }) — directional slide + opacity (default for tooltip)
• fade — simple opacity transition
• scaleAndFade — scale from 0.95 + opacity (suitable for menus/dropdowns)

Dialog animation

Pass a preset to Dialog.Content:

import { dialogSlideUpAndFade } from '@atlaskit/top-layer/animations';

const animation = dialogSlideUpAndFade();

<Dialog.Content animate={animation}>
	<Dialog.Surface>...</Dialog.Surface>
</Dialog.Content>;

Available dialog presets:

• dialogSlideUpAndFade({ distance? }) — slide up + opacity with backdrop fade (matches legacy modal entrance)
• dialogFade — simple opacity + backdrop fade

Progressive enhancement

Browsers without @starting-style support will show/hide elements instantly — no broken state. The prefers-reduced-motion: reduce media query sets all transition durations to 0s.

Accessibility

Browser tests in __tests__/playwright/ verify the following WCAG 2.2 success criteria. See notes/goals/accessibility-criteria.md and notes/audits/accessibility-audit-report.md for details.

| A11y criterion | Browser test | | ------------------------------------ | ------------ | | 1.3.1 Info and Relationships | ✓ | | 1.3.2 Meaningful Sequence | ✓ | | 2.1.1 Keyboard | ✓ | | 2.1.2 No Keyboard Trap | ✓ | | 2.4.3 Focus Order | ✓ | | 2.4.7 Focus Visible | ✓ | | 2.4.11 Focus Not Obscured | ✓ | | 3.2.1 On Focus | ✓ | | 4.1.2 Name, Role, Value | ✓ | | 4.1.3 Status Messages | ✓ | | Background inertness (modal dialogs) | ✓ | | Close reasons (Dialog) | ✓ |

Documentation

See notes/ for project documentation, architecture decisions, migration records, and audit reports. The notes/README.md provides a full index.